Spray booth



' May 31, 1938. J LUDWIG 2,119,282

SPRAY BOOTH Filed Aug. 24, 1936 INVENTOR.

BY f QJHNE. LUUWIE WQ ATTORNEY.

Patented May 31, 1938 SPRAY BOOTH John E. Ludwig, Detroit, Mich,assignor to De Vilbiss Company, Inc., Toledo, Ohio, a corporation ofOhio Application August 24, 1936, Serial No. 97,533

11 Claims.

My. invention pertains to ventilated spraying booths and moreparticularly to spraying booths of the type suitable for continuousproduction spraying.

It is an object of my invention to provide a ventilated spraying boothcomprising a forced alrinlet header having air directing meansassociated therewith for directing a flow of air downwardly atrelatively low velocity adjacent the object being sprayed and havinghigh velocity air projecting means for projecting a thin blast or sheetof air downwardly at high velocity between the object and the lowvelocity air to aid the operator in applying a smooth even coating ofpaint on the object and to protect him from inhaling the poisonous fumesthereof.

It is a further object of my invention to provide a spraying boothcomprising an air ventilating means wherein fresh air'is forced into the20 spraying booth through an inlet header which comprises lowvelocityvdirecting outlets on the lower wall at opposite sides of thehousing for directing a large volume of air downwardly at low velocityon opposite sides of the object being 25 sprayed, also narrow airprojecting nozzles for projecting thin sheets of air downwardly at highvelocity adjacent the opposite sides of the object between the objectand the low velocity air,v and additional air projecting means forprojecting a 3 sheet of air at high velocity across the ceiling betweenthe downwardly projected air streams. The purpose of this sheet of airat high velocity crossing the ceiling is not only to aid in carrying ofifumes, but it is also useful in preventing the curtains of high velocityair from creating a vacuum adjacent the object being sprayed which wouldthen otherwise tend to cause said high velocity air streams to hugtightly to the object being sprayed. This laterally projected airsubsequent to its travel across the ceiling moves downwardlycomparatively slowly between the downwardly projected high velocity airstreams permitting them to maintain a substantially direct path frominlet tooutlet.

It is also an object of my invention to provide a ventilated sprayingbooth comprising a floor having spaced exhaust apertures therein, anexh'aust fan for drawing air rapidly from the booth through theexhaust'apertures, an air intake fan having air directing means fordirecting a volume of fresh air downwardly on opposite sides of theobject to be sprayed, and air projecting nozzles for directing thinsheets of air downwardly at high velocity adjacent the opposite sides ofthe object between the object and the large volume of downwardlydirected air whereby the ventilating air is aided by gravity in carryingthe obnoxious spray vapors awayfrom the operator.

The invention, however, both as to it's organization and its method ofoperation together with additional objects and advantages thereof willbest be understood from the following descript-ion of a specificembodiment, when read in conjunction with the accompanying drawing, inwhich:

Fig. 1 is a side elevational view of my ventilated paint spraying boothpartially sectioned and .broken away to clearly show the internalconstruction thereof and the circulation of air provided therein;

Fig. 2 is an enlarged sectional view thereof showing the arrangement ofthe ,inlet header with the high velocity air projecting nozzles and thelow velocity air directing grills; and

Fig. 3 is an elevational view of a low velocity air admitting grillprovided in one side of the ventilating header.

Referring more particularly to Figs. 1 and 2 of the drawing, myventilated spray booth comprises a housing enclosed by side walls I and3 and a roof 5 through which the objects to be sprayed are continuouslypassed. The spray housing is provided with a floor I spaced above thefloor 9 of the factory and provided with apertured exhaust grills H andI3 which are spaced from the side walls i and 3 of the housing. Theexhaust grills H and I3 are extended horizontally along the floor I ofthe housing, and may comprise any suitable open-work grating or thelike. The objects to be sprayed are transported through the sprayboothover the floor "I and between the exhaust grills II and I3 in anyconvenientmanner as on an endless conveyor for example.

For supplying ventilating air to the spray booth, I provide a motorizedexhaust fan l5 therein for drawing air through an air intake conduit Hwhich extends upwardly and passes through the roof ill of the factory,where fresh air is drawn in through an elbow-2|.

For properly distributing the ventilating air in the spray booth tocarry the poisonous fumes away from the workman and to aid him inproperly distributing the sprayed material to provide a smooth coat uponthe object, the lower end of the intake air conduit i1 is provided witha transversely disposed header 23 of flat shallow construction which istransversely disposed in the spraying booth over the objects to besprayed.

sprayed. The panel 29 extends the length of the header between the endwalls thereof and is provided with marginal flanges 3| and 33 at itsleft and right hand edges respectively which are turned upwardly in asubstantially vertical position. Parallel to and spaced from theupturned flange 33 at the right hand edge of the panel 29, I provide avertical partition 35 which rises from the lower wall of the intakeheader.

The uppermost edge of the partition 35 is provided with a vane 39 whichis turned horizontally toward the center of the header and issuitablyspaced from the upper wall 31 of the header to deflect the airand to define an air inlet conducting passage of suitable size forreceiving the air which passes downwardly through the grill 21 of theheader with relatively "low velocity. The vertical panel-flange 33likewise carries at its upper edge vane portion 4| turned toward thecenter of the header and which, with the vane 39, defines a passage fordeflecting and receiving the proper volume of air which passesdownwardly through the duct defined between the flange 33 and thepartition 35 into the spray booth. The vertical walls 33 and 35 thusdefine a nozzle for projecting a flat blast or sheet of air downwardlywith high velocity adjacent the side of the object being sprayed andbetween it and the larger volume of low velocity air which is directeddownwardly from the grill 21.

For directing a sheet of high velocity air under and adjacent to theconcave face of the closed panel 29, I provide a vertically disposedpartition wall which extends across the header in spaced relation fromthe left hand panel-flange 3| and which, along its lower edge, isprovided with a horizontally disposed flange 45 which projects underandspaced from the closed panel 29. The air deflecting flange 45 isprovided along its edge with an upturned vane portion 41 which is spacedsubstantially parallel with the under surface of the panel 29 whereby athin jet or sheet of air is projected at high velocity along the underside of the panel 29 toward the jet of air which is projected downwardlyfrom the right hand side of the panel 29. The vertical partitions 3| and43 are preferably provided at their upper edges with deflecting vanes44- and 46 respectively turned toward the center of the header.

For projecting a high velocity sheet of air downwardly adjacent the lefthand side of the object being sprayed, I provide a vertical partltion 49which passes through the header in par allel spaced relation from thepartition 43 and defines a high velocity projecting duct therebetween.This high velocity nozzle projects a sheet of air downwardly between theobject being sprayed and the larger volume of low velocity air passingdownwardly from the grill 25 at the left hand side of the panel 29. Theupper edge of the partition 49 is provided with a horizontally disposedflange 5| which projects 4 toward the middle of the header and isspaced. from theupper wall 31 of the header for defining an airconducting passage suitable for passing a proper volume of air from theconduit through the low velocity grill 25. The low velocity air inletgrills 25 and 21 respectively may be of any suitable open-work but Ipreferably providea grill comprisinga plurality of metallic bars 53securedtogether in parallel relation by transversely disposed rods 55,as shown in Fig. 3. For providing eflicient illumination, a circularaperture 58 is provided in the center of the grill for mounting thereflector and defusing globe of a suitable illuminating unit which, aswill be readily understood, may be of suitable streamlined conformationto avoid setting up eddies in the air stream.

F or efliciently exhausting the air from the spray booth and to aid theair projecting nozzles and grills in providing a smooth uniformcirculation of the air therein, I provide an exhaust fan 51 which isconnected through a conduit 59 which connects into the air space definedunder the floor 1. At the left hand side of the exhaust grill II, apartition 61 is preferably inserted for restricting the exhaust passagedefined thereunder.

In operation, the objects to be sprayed are moved through the spraybooth in any suitable manner as upon a continuous conveyor (not shown),and as the attendant standing at one side of the spray booth sprays theobject, the

high velocity sheets of air 1| and 13 respectively projected downwardlyon opposite sides of the object tend to protect him effectively frominhaling the poisonous vapors.

If the paint spray is discharged strongly against the object beingcoated there is considerable rebound of spray fumes which occasionallypenetrate the high velocity streams. The addition of low velocity airbetween the object and high velocity streams impedes the rebound andthereby assists the high velocity streams in preventing the fumes fromreaching the operator.

Also the larger steams 15 and 11 of low velocity air projecteddownwardly from the grills 25 and 21 insure the sprayer a fresh supplyof air at all times, and the circulation of the air above andaround theobject at all times aids in properly applying a smooth coat of thesprayed material upon the object.

The jet of high velocity air coming through the passage between thevertical partitions 3| and 43, and which starts out in the direction ofthe arrows under the panel 29 becomes substantially two low velocitystreams of air passing downwardly on each side of the article beingsprayed, due to the eddies or suction effect set up between highvelocity streams 1| and 13.

The turns and narrow sections of the passage for the air passing betweenvane 41 and panel 29 prevent the resulting air jet from having as muchbulk or as high velocity as the vertical sheets of air 1| and 13. Ittherefore is lacking in carrying power and is influenced by the downwardpull of the suction set up by the high velocity sheets 1| and 13. Aportion of the jet near sheet 1| will be attracted by it and travel withit to the exhaust opening while a major part of the jet will continueforwardly until it is turned downwardly by sheet 13. The generaldownward movement of the air jet is caused by the pull of the air sheets1| and 13 and has therefore less velocity than have these sheets.

The above advantages are also augmented by gravity when the air inletsare above the outlets. In applicant's construction more effectiveprotection is provided for the attendant whereby he can closely andclearly see his work.

Although I have shown and described a specific embodiment of myinvention, I am aware that many modifications are possible, my inventiontherefore is not to be restricted except insofar as it is limited by theprior art and the scope air inlet header associated therewith, lowvelocity directing means connected with said header for directing alarge volume of air to flow in a path adjacent the object being sprayed,and an air projecting nozzle for projecting a sheet of air at highvelocity between said large volume of moving air and the object beingsprayed.

2. A ventilated spray booth having air supply means for supplying freshair to said booth, an air inlet header connected therewith, an opengrill in the lower wall of said header for directing a large volume ofair to fiow in a path adjacent the object being sprayed, and anelongated air projecting nozzle opening from the lower face of saidheader for projecting a thin sheet of air to flow downwardly at highvelocity between said large volume of downwardly flowing air and theobject being sprayed.

3. A ventilated spray booth having air supply means for supplying freshair to said booth, an air inlet header connected therewith, spaced airprojecting nozzles for sheets of air at high velocity on opposite sidesof objects to be sprayed and means for supplying lower velocity airbetween said sheets of air at high velocity.

4. A ventilated spray booth having an air inlet conduit for supplyingfresh air to said booth, an air intake fan for forcing the airdownwardly through said conduit, an air inlet header connectedtherewith, low velocity air directing means in the lower face of saidheader at opposite sides thereof comprising an open grill work fordirecting large volumes of air downwardly on opposite sides of theobject being sprayed, elongated slots in the lower face of said headerat the adjacent edges of said spaced grills for directing thin sheets ofair downwardly at high velocity adjacent the inside each stream of slowmoving air.

5. A ventilated spray booth having a housing enclosed by side walls anda roof for defining the space through which objects are transported tobe sprayed, a floor in said housing, spaced exhaust apertures in saidfioor, for drawing air from said booth at opposite sides of the sprayedobject, an exhaust fan connected for drawing air therefrom, an airsupply conduit for supplying fresh air in said housing, an intake fanassociated therewith for forcing air downwardly through said conduit, anair inlet header connected therewith, low velocity air directing meansfor directing streams of air downwardly adjacent opposite sides of thesprayed object, and high velocity air projecting means associated withsaid header for projecting thin sheets of air downwardly at highvelocity on both sides of the sprayed object between the object and theslowly moving streams of air.

6. A ventilated spray booth having a housing for enclosing a spacethrough which objects may be passed for spraying comprising side wallsand a roof, a floor in said housing, spaced exhaust apertures in saidfloor, an exhaust fan for drawing air rapidly from said housing throughsaid exhaust apertures, an air inlet conduit for supplying fresh air tosaid housing, an air intake fan for forcing air downwardly through saidconduit, an air inlet header connected therewith,

high velocity air projecting means associated therewith for projectingthin sheets of air downwardly at high velocity in spaced relation towardthe spaced exhaust apertures in said floor, and low velocity airdirecting outlets in said header for directing large volumes of airdownwardly outside of said high velocity sheets of air.

7. An air inlet header for ventilating a paint spraying booth comprisingan elongated casing of flattened conformation adapted to be connectedwith an air inlet conduit, a solid ceiling panel extending across themiddle of the lower wall of said casing, air outlets of substantiallybroad area on opposite sides of said panel, and elongated slotsextending along the opposite edges of said panel adjacent said outletsfor projecting thin sheets of air therefrom.

8. An air inlet header for ventilating a paint spraying booth comprisingan elongated casing of flattened conformation adapted to be connectedwith an air inlet conduit, a solid ceiling panel extending across themiddle of the lower wall of said casing, air outlets of substantiallybroad area in the lower face of said header on opposite sides of saidpanel, elongated slots along the opposite edges of said panel adjacentsaid outlets for projecting thin sheets of air therefrom at highvelocities, spacedpartition walls projecting into said header from theopposite edges of said slot for defining an air projecting nozzle andpassage connecting from the interior of said header.

9. An air inlet header for ventilating a paint spraying booth comprisingan elongated casing of flattened conformation adapted to be connectedwith an air inlet conduit, a solid ceiling panel extending across themiddle of the lower wall of said casing, air outlets of substantiallybroadarea in the lower wall of said header on opposite sides of saidpanel, elongated slots along the opposite edges of said panel adjacentsaid outlets for projecting thin sheets of air therefrom, spacedpartition walls projecting into said header from the opposite edge ofsaid slot for defining an air projecting nozzle and passage connectingfrom the interior of said header, a ceiling panel ventilating slotextending adjacent one edge of said panel, and an air projecting -vaneconnected from the lower edge of said slot spaced from and substantiallyparallel to the lower face of said panel for-directing a thin sheet ofair thereacross.

10. An air inlet header for ventilating a paint spraying boothcomprising a flat casing having air outlets of broad area spaced in thelower wall on opposite sides of the header, a solid panel disposed inthe lower face of said casing between said outlets, said panelcomprising a concave lower face, an air projecting nozzle for projectinga thin stream of air at high velocity across the lower face of saidpanel, spaced air projecting nozzles of elongated conformation disposedon opposite sides of said panel for projecting thin sheets of airdownwardly at high velocity therefrom, and partition walls projectinginwardly into said header from the opposite sides of said slots fordefining air ducts or nozzles leading thereto and for providingsufficient back pressure to project the high velocity blasts of airwhile directing a suitable volume of air to supply the large lowvelocity openings.

11. A ventilated spray booth having air supply means for supplying freshair to said booth, an air inlet header associated therewith, a dischargenozzle for projecting a sheet of air at high velocity to one side of theobject being sprayed and discharge means for projecting air at lowvelocity on both sides of the sheet'of high velocity air.

JOHN E. LUDWIG.

